[Not Applicable]
1. Field of the Invention
The present invention relates to a golf club head with a face composed of a forged material. More specifically, the present invention relates to a golf club head with face composed of a thin forged material for a more efficient transfer energy to a golf ball at impact.
2. Description of the Related Art
When a golf club head strikes a golf ball, large impacts are produced that load the club head face and the golf ball. Most of the energy is transferred from the head to the golf ball, however, some energy is lost as a result of the collision. The golf ball is typically composed of polymer cover materials (such as ionomers) surrounding a rubber-like core. These softer polymer materials having damping (loss) properties that are strain and strain rate dependent which are on the order of 10-100 times larger than the damping properties of a metallic club face. Thus, during impact most of the energy is lost as a result of the high stresses and deformations of the golf ball (0.001 to 0.20 inch), as opposed to the small deformations of the metallic club face (0.025 to 0.050 inch). A more efficient energy transfer from the club head to the golf ball could lead to greater flight distances of the golf ball.
The generally accepted approach has been to increase the stiffness of the club head face to reduce metal or club head deformations. However, this leads to greater deformations in the golf ball, and thus increases in the energy transfer problem.
Some have recognized the problem and disclosed possible solutions. An example is Campau, U.S. Pat. No. 4,398,965, for a Method Of Making Iron Golf Clubs With Flexible Impact Surface, which discloses a club having a flexible and resilient face plate with a slot to allow for the flexing of the face plate. The face plate of Campau is composed of a ferrous material, such as stainless steel, and has a thickness in the range of 0.1 inch to 0.125 inch.
Another example is Eggiman, U.S. Pat. No. 5,863,261, for a Golf Club Head With Elastically Deforming Face And Back Plates, which discloses the use of a plurality of plates that act in concert to create a spring-like effect on a golf ball during impact. A fluid is disposed between at least two of the plates to act as a viscous coupler.
Yet another example is Jepson et al, U.S. Pat. No. 3,937,474, for a golf Club With A Polyurethane Insert. Jepson discloses that the polyurethane insert has a hardness between 40 and 75 shore D.
Still another example is Inamori, U.S. Pat. No. 3,975,023, for a Golf Club Head With Ceramic Face Plate, which discloses using a face plate composed of a ceramic material having a high energy transfer coefficient, although ceramics are usually harder materials. Chen et al., U.S. Pat. No. 5,743,813 for a Golf Club Head, discloses using multiple layers in the face to absorb the shock of the golf ball. One of the materials is a non-metal material.
Lu, U.S. Pat. No. 5,499,814, for a Hollow Club Head With Deflecting Insert Face Plate, discloses a reinforcing element composed of a plastic or aluminum alloy that allows for minor deflecting of the face plate which has a thickness ranging from 0.01 to 0.30 inch for a variety of materials including stainless steel, titanium, KEVLAR (copyright), and the like. Yet another Campau invention, U.S. Pat. No. 3,989,248, for a Golf Club Having Insert Capable Of Elastic Flexing, discloses a wood club composed of wood with a metal insert.
Although not intended for flexing of the face plate, Viste, U.S. Pat. No. 5,282,624 discloses a golf club head having a face plate composed of a forged stainless steel material and having a thickness of 3 mm. Anderson, U.S. Pat. No. 5,344,140, for a Golf Club Head And Method Of Forming Same, also discloses use of a forged material for the face plate. The face plate of Anderson may be composed of several forged materials including steel, copper and titanium. The forged plate has a uniform thickness of between 0.090 and 0.130 inch.
Another invention directed toward forged materials in a club head is Su et al., U.S. Pat. No. 5,776,011 for a Golf Club Head. Su discloses a club head composed of three pieces with each piece composed of a forged material. The main objective of Su is to produce a club head with greater loft angle accuracy and reduce structural weaknesses. Finally, Aizawa, U.S. Pat. No. 5,346,216 for a Golf Club Head, discloses a face plate having a curved ball hitting surface.
The Rules of Golf, established and interpreted by the United States Golf Association (USGA) and The Royal and Ancient Golf Club of Saint Andrews, set forth certain requirements for a golf club head. The requirements for a golf club head are found in Rule 4 and Appendix II. A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Although the Rules of Golf do not expressly state specific parameters for a golf club face, Rule 4-1e prohibits the face from having the effect at impact of a spring with a golf ball. In 1998, the USGA adopted a test procedure pursuant to Rule 4-1e which measures club face COR. This USGA test procedure, as well as procedures like it, may be used to measure club face COR.
Although the prior art has disclosed many variations of face plates, the prior art has failed to provide a face plate with a high coefficient of restitution composed of a thin material.
The present invention provides a golf club head with a striking plate having a high coefficient of restitution in order to increase the post-impact velocity of a golf ball for a given pre-impact club head velocity. The present invention is able to accomplish this by using a striking plate composed of a thin material, having a small aspect ratio (near 1.0) and having a large surface area.
One aspect of the present invention is a golf club head having a striking plate having a thickness in the range of 0.010 inch to 0.250 inch, and having a coefficient of restitution of at least 0.83 under test conditions, such as those specified by the USGA. The standard USGA conditions for measuring the coefficient of restitution is set forth in the USGA Procedure for Measuring the Velocity Ratio of a Club Head for Conformance to Rule 4-1e, Appendix II. Revision I, Aug. 4, 1998 and Revision 0, Jul. 6, 7998, available from the USGA.
Another aspect of the present invention is a golf club head including a face member, a crown and a sole. The face member is composed of a material selected from titanium, titanium alloys, steels, vitreous metals, composites and ceramics. The face member includes a striking plate for striking a golf ball, a face extension and an interior tubing. The face extension extends laterally inward from a perimeter of the striking plate. The interior tubing receives a shaft and engages an upper portion of the face extension and a lower portion of the face extension. The crown is secured to the upper portion of the face extension at a varying distance from the striking plate. The sole plate is secured to the lower portion of the face extension at a varying distance from the striking plate.
Yet another aspect of the present invention is a golf club head having a striking plate with an aspect ratio no greater than 1.7. The aspect ratio is the ratio of width of the face to the height of the face. Normally, the aspect ratios of club head faces are relatively greater than 1.7. For example, the aspect ratio of the original GREAT BIG BERTHA(copyright) driver from Callaway Golf Company of Carlsbad, California was 1.9. As described in greater detail below, the smaller aspect ratio of the striking plate of the club head of the present invention allows for greater compliance and thus a larger coefficient of restitution.
Yet another aspect of the present invention is a golf club head including a body composed of a titanium material and having a volume in the range of 175 cubic centimeters to 400 cubic centimeters, and preferably 260 cubic centimeters to 350 cubic centimeters, and most preferably in the range of 300 cubic centimeters to 310 cubic centimeters, a weight in the range of 160 grams to 300 grams, preferably 175 grams to 225 grams, and a face having a surface area in the range of 4.50 square inches to 5.50 square inches, and preferably in the range of 4.00 square inches to 7.50 square inches.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.